If you have a CT scan, MRI or ultrasound done at SPH (even xrays done through the emergency department), the resultant images are stored in digital form on the SPH radiology web site. Right now access to the SPH radiology site is limited to physicians with SPH privileges and patients aren't emailed their images. What I have been doing, in the case of interesting scans, is to download the images to my office system where they are available for perusal. For a limited period of time, I will be providing online access to patient images through this web site. These will be made available as follows: a folder called images will be the root folder for all patient radiology data and for each patient, a unique folder name will be created which appears to be a random sequence of numbers and digits at least 20 characters long. When I have created this folder and put image files into it, I will email you the URL of your image folder. Unless you disclose this URL to anyone else, only you and I are able to access the data in your image folder. The same mechanism can be applied to making other laboratory results available on an individual basis. Anyone who is familiar with how html protocol works (assuming one has a secure web server) can see that this method of allowing people access to their lab results is reasonably secure; if your security requirements are higher, then public key encryption can be used to encrypt lab results if desired.

For the moment, web access to patient image files will be free. This state of affairs will exist only during the testing phase of this project. Once the system has been debugged, lab results will be available for a fee which will reflect the cost of having the necessary files transferred to my computer. Unfortunately this is a manual process for the moment as SPH radiology only makes files available via web server. My options in getting data from such a source are either to do it manually, or to write a scripting language which will allow me to automate the process of obtaining most recent patient imaging results from a web server. This is doable, but I have to remind myself that my first job is medicine, not programming (although the latter is starting to seem more and more appealing recently).

Format of radiology data will be as jpeg files for the moment, but it should be noted that this is often an inferior format to use. CT and MRI images contain pixels which are 16 bits in length. The range of values of interest is often very small, and in the case of a brain CT may represent only 64 steps out of a pixel range of 0-2000. When images are transferred to film, appropriate pixel value windows are used to create a gray-scale image that best shows up the areas of interest. Jpeg results in great compression ratios, but this is lossy compression. When one takes a brain CT slice and makes a jpeg image out of it, there is no way that one can redisplay the slice optimized for bone windows since these have all been mapped onto whatever pixel represents maximal whiteness. To get raw pixel data corresponding to a CT or MRI scan is possible, but these are large files (OK, not as large as they used to appear 13 years ago when a 10 Mb HDD was still considered to be impressive). There is a common format which is used to encode such files, and details of this format can be found by looking at DICOM specifications here. DICOM format files have the *.pap extension and are viewed using the Osiris viewer which is available from the following site. Unfortunately it is an object code only viewer as source code is furnished only to developers, but this doesn't seem to be an overly onerous registration process. If you want, I can get the pap files in your personal directory rather than jpegs and you can view them with Osiris (you have to get your own copy of this program). I will not be providing regular xray pictures in DICOM format since there are huge files on the order of 20-40 Mb in size.

One of my projects is to create a web based electronic patient record (EPR) which contains all laboratory results, diagnostic images, etc. If you moved to another city, all you would have to do would be to give your new doctor your unique patient directory name and my webserver URL. I've had to arrange to get xrays and CT scans to go along with people and not only is this a pain in the ass to do, but there is generally only one copy of the xray or scan. With digitiezed images, you make a new copy whenever you need it. Ensuring that EPR data has not been altered is done by digitally signing each item with a PGP signature using my private key. My PGP public key is given here and it can be used to verify the authenticity of the signed digital object.